1. Field
One or more embodiments described herein relate to a method and apparatus for fabricating a semiconductor device.
2. Description of the Related Art
Regression analysis is an area of inferential statistics which analyzes relationships (e.g., causal relationships) among two or more variables. A regression analysis may be performed based on a mathematical functional equation corresponding to changes in variable values. Using this equation, a correlation between the changes may be inferred. The functional equation may be referred to as a regression equation.
According to one technique, a regression equation is used to analyze what relationship exists between a change in a particular variable (e.g., an independent variable or an explanatory variable) and a change in another variable (e.g., a dependent variable) and the change in which variable is the cause and the change in which variable is the resultant phenomenon. A regression analysis is different from a correlation analysis, which simply investigates the closeness of relationships among variables, not the causal relationships among the variables.
To fabricate a semiconductor device, layers may be aligned with each other by measuring an overlay of a semiconductor wafer. A regression analysis using a regression equation may be performed in the alignment process. The precision and accuracy of the regression analysis may be expected to increase as the regression equation includes higher-order terms. However, a high-order regression equation may experience the problem of multicollinearity, which may threaten the reliability of the process of fabricating a semiconductor device.